Automotive vehicles may include passive entry systems that allow a user to access and start a vehicle just by holding a key, key fob or card. In operation, such systems may perform and/or enable vehicle access and vehicle start functions based on a determined location of the key in or around the vehicle.
To facilitate determining key location, the key, key fob or card may be equipped with a transceiver with one or more antennas, and the passive entry system may employ one or more transceivers with multiple antennas positioned at different locations in the vehicle. The passive entry system may also include an Electronic Control Unit (ECU) or controller having a decision based algorithm that determines key location based on the transmission of radio frequency (RF) or low frequency (LF) signals (e.g., 125 kHz) between the key antenna and the vehicle based antennas.
Current passive entry systems use low frequency (LF) antennas located in the vehicle door handles and trunk. Such systems provide relatively small, concentrated lock/unlock zones just around the individual doors and trunk areas. As previously noted, the locking/unlocking functions occur as a result of wireless communication with a key fob.
As a result, there exists a need for a vehicle remote function system and a method for determining locations of the fob more precisely relative to the vehicle. Such a system and method would determine fob locations inside and/or outside the vehicle using adaptive filtering of ultra-wide band wireless signals communicated between the fob and vehicle mounted antennas.